In recent years, imaging devices, such as digital cameras, have been widely spread, and there are some imaging devices provided with a function to automatically and optimally adjust focus and exposure according to an image capturing scene. However, special stage effects, such as adjustment of a composition and shading off of a background at the time of capturing an image, are still largely depending on skills of users. Especially, for beginners who do not have knowledge of cameras, it is difficult to capture an image with the special staging effects. Therefore, in recent years, many technologies to shade off the background, and the like have been proposed (PTL 1).